This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Histone deacetylase (HDAC) inhibitors are epigenetic modifiers which obstruct the removal of an acetyl groups from an [unreadable]-N-acetyl lysine on both histone or non-histone proteins. By altering gene expression, one result is cell cycle blockage at the G1 phase. Synthetic HDAC inhibitors are being tested for multiple biomedical applications including inhibition of tumor cell proliferation and the induction of immune tolerance. Unfortunately, histone deacetylase inhibitors efficacy has been limited by their short half-life in vivo. The goal of this proposed research is to increase the bioavailability of HDAC inhibitors in vivo by the derivization of Vorinostat[unreadable] a class 1 HDAC inhibitor. We will start with Vorinostat, and attempt to modify it for increased stability and enhanced tumor targeting capacity. Although Vorinstat, has been approved as a treatment for cutaneous T-cell lymphoma, animal studies have found that this HDAC inhibitor breaks down within minutes thereby reducing its bioavailability. Structurally, Vorinostat maintains a carbon linker, and a hydrophobic cap, and a Zn2+-chelating hydroxamic acid. Although the hydroxamic acid is the functional region of Vorinostat its ability to be catalyzed under biological conditions decreases the half-life of Vorinostat in vivo. This project will synthesis and biologically evaluate novel N-hydroxy cyclic imides, N-alkyloxy esters, and polyethylene glycol (PEG)-linked Vorinstat derivatives designed for increased bioavailability by enhancing molecular stability of the hydroxamic acid and cellular targeting of Vorinostat derivatives. Targeting of the Vorinostat derivatives should allow for improved efficacy due to direct interaction with only the desired cancer cells. Structural confirmation and stability studies of the Vorinostat derivatives will use gas chromatography mass spectrometry (GCMS), infrared (IR), and nuclear magnetic resonance (NMR) spectroscopy. Two general protein assays (Apoptosis and Cell Proliferation Analysis) will be conducted for all Vorinostat derivatives in which EL4 cells (mouse T cell lymophoma) will determine specific biological activity using flow cytometry.